The objective of the proposed research is to determined whether undernutrition during the period of normal synapase formation retards permanently the morphological development of neuronal processes and synapses. The rodent lateral geniculate body, taken as a model of brain tissue, will be studied in depth by a variety of morphological techniques, including Nissl and Golgi preparations quantiative electron microscopy to investigate possible alterations in neuropil volume, synaptic packing density and morphology, and neuronal branching resulting from the effects of early postnatal undernutrition. The development of specific interneuronal connections (synapses) is considered to be of fundamental importance in functioning nervous systems and failure of normal synaptic development could be expected to result in retarded brain function. The research investigates cellular and subcellualr mechanisms in subnormal brain development and may have relevance to the pathophysiology of developmental neurological disorders such as congenital mental retardation.